JPH0665200B2 - High-speed atomic beam source device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-speed atomic beam source apparatus for efficiently and easily obtaining a high-speed atomic beam.

<Prior Art> As a conventional method of obtaining a high-speed atomic beam, there is a method of irradiating an ion beam with a thermoelectron beam to bond the ions and electrons to neutralize the ions to form a high-speed atomic beam. Another method is to introduce an ion beam into a charge exchanger filled with high-density gas atoms / molecules and collide the ion beam with gas molecules to lose the electric charge from the ions to form a fast atom beam. Is.

<Problems to be Solved by the Invention> In the conventional method described above, an ion source for obtaining an ion beam and a thermionic electron source for supplying a thermionic beam are necessary, or a high-density gas atom / molecule is introduced. However, the device is complicated and expensive. Furthermore, the efficiency of conversion from ion beam to high-speed atom beam is several to 20%.
The disadvantage was that it was very low. The present invention has been made in view of the above-described conventional technique, and an object of the present invention is to provide a high-speed atomic beam source device capable of obtaining a high-speed atomic beam easily, inexpensively, and efficiently.

<Means for Solving the Problems> In the structure of the fast atom beam source according to the present invention which achieves such an object, cathodes are arranged on both sides of the anode and the anode is held at a high potential with respect to the cathode. By
A glow discharge is generated between the anode and the cathode, and electrons are oscillated between the both cathodes with the anode as the center, while the particle beam outlet is connected to the cathode and a cylindrical neutralizing mechanism directly connected to the particle beam outlet. Is provided, the ions having passed through the extraction port are made to collide with the inner wall of the neutralization mechanism to form a high-speed atomic beam.

<Operation> Electrons oscillating between the cathodes around the anode collide with gas molecules to form plasma, and positive ions in the plasma are attracted to the cathode and accelerated. Then, the positive ions enter the neutralization mechanism through the particle beam extraction port and collide with the side wall in the neutralization mechanism. Ions that collide with the side wall combine with secondary electrons generated by ion bombardment from the side wall to neutralize and become a fast atom beam, or they undergo charge conversion when they collide with the side wall and become a fast atom beam. .

<Example> Hereinafter, an example of the present invention will be described in detail.

FIG. 1 shows a fast atom beam source device according to an embodiment of the present invention. As shown in the figure, both end surfaces of a hollow cylindrical cathode case serve as cathodes 3 and 4, and the cathodes 3 and 4 are grounded, while the cathode 4 is provided with a gas inlet 1. There is. Inside the cathode case, round bar-shaped anodes 2 are arranged above and below the center of the cathode case, and are connected to a power supply 8 provided outside. On the other hand, a particle beam outlet 5 is provided in the center of the cathode 3, and a cylindrical neutralizing mechanism 6 is directly connected to the particle beam outlet 5.

The high-speed atomic beam source device of this embodiment having the above structure is used as follows.

First, an inert gas or an active gas is introduced into the cathode case from the gas introduction port 1 to about 10 ^-1 Torr to 10 ^-3 Torr,
The anode 2 is held at a high potential of several 100V to several kV with respect to the cathodes 3 and 4. Then, while a claw discharge occurs between the anode 2 and the cathodes 3 and 4, the electrons emitted from the cathodes 3 and 4 at this time accelerate toward the anode 2 and pass through the middle of the two anodes 2 on the opposite side. It loses its velocity through the cathodes 4 and 3 and is accelerated toward the anode 2 to repeat the above-mentioned behavior. A high-frequency vibration called the so-called Barkhausen-Kurz vibration is generated between the cathodes 3 and 4 with the anode 2 as the center, and the vibrating electrons collide with gas molecules to effectively form plasma. The Rukoto. The positive ions in the formed plasma are attracted to the cathodes 3 and 4 to be accelerated, and pass through the particle beam extraction port 5 to enter the neutralizing mechanism 6 having a cylindrical shape. When the incident ion beam collides with the side wall in the neutralization mechanism 6, the ion beam is combined with the secondary electron generated by the ion bombardment from the side wall to be neutralized and becomes a fast atom beam.
Further, when the ion beam collides with the side wall of the neutralization mechanism 6, charge conversion may be performed, and the ion beam may become a high-speed atom beam. Further, the electrons oscillating in the Barkhausen-Kurz are bound to the ions and neutralized near the cathode 3 where the velocity is 0, and fast atoms are created. Due to such a main mechanism, the ion beam becomes a fast atom beam and is emitted from the neutralization mechanism 6 into the vacuum.

The material of the neutralization mechanism 6 is preferably one having a high secondary electron emission ratio and a small spatter rate. This is because if the secondary electron emission ratio is high, the probability of recombination with ions to form fast atoms is increased, and contamination by atoms constituting the neutralization mechanism can be prevented. In this embodiment, the neutralization mechanism 6 is composed of the sintered graphite having a high secondary electron emission ratio of about 0.5 and a low spatter rate of about 0.1. Further, in the present embodiment, two rod-shaped ones were used as the anode 2, but if it does not interfere with the electrons oscillating in the Barkhausen-Kurz or the ions accelerating toward the cathode 3, a ring-shaped or other A shape can be used. Furthermore, in this embodiment, the particle beam outlet 5 and the neutralization mechanism 6 are provided only on the cathode 3, but the present invention is not limited to this, and may be provided on both cathodes 3 and 4.

Next, the actually measured neutralization rate of the high-speed atomic beam source device of the above embodiment will be described. The neutralization rate is the ratio of the fast atom beam in the particle beam consisting of the ion beam and fast atom beam extracted from the source when Ar gas is introduced into the fast atom beam source device.

The apparatus shown in FIG. 2 was used to measure the neutralization rate. As shown in the figure, two slits 9 and 10 are installed in parallel in the exit image of the neutralization mechanism 6, and parallel plate type deflection electrodes 11 are provided above and below the slits 9 and 10. , 12 are arranged to change the voltage Vd applied to the deflection electrodes 11 and 12 so that the current i flowing through the collector 13 can be measured. Assuming that the particle beam does not contain electrons, the neutralization rate Rn ₀ is expressed by the following equation (1).

Where N ₀ is the ion current conversion value of high energy particles flowing into the collector, N ₊ is the ion beam current value flowing into the collector, δ is the secondary electron emission ratio, and i ₀ is the collector when the deflection voltage Vd = 0. The current id is the saturation value of the collector current when the deflection voltage is applied.

FIG. 3 shows changes in the collector current i when the deflection voltage Vd is changed for two operating conditions.
Under all operating conditions, i ₀ ≈id, and substituting this into equation (1) results in Rn ₀ ≈1. That is, according to the present invention, a high-speed atomic beam having a neutralization rate of almost 100% can be extracted.

<Effects of the Invention> According to the fast atom beam source apparatus to which the present invention is applied as specifically described based on the above embodiments, the fast atom beam can be extracted efficiently at low cost, easily and efficiently. Since a fast atom beam has no electric charge, when an insulating sample is irradiated with this, there is an advantage that processing such as etching, sputtering, and ion implantation proceeds without being affected by the surface potential such as surface charging. Even when a semiconductor sample is irradiated, there is an advantage that surface damage accompanied by an increase in interfacial charge density, which is a problem in the case of an ion beam or the like, is unlikely to occur.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the device of the present invention, and FIG.
FIG. 3 is a configuration diagram of an experimental apparatus for measuring the neutralization rate, and FIG. 3 is a graph showing the results of the neutralization rate measurement experiment of the apparatus of the present invention. In the drawing, 1 is a gas inlet, 2 is an anode, 3 and 4 are cathodes, 5 is a particle beam outlet, 6 is a neutralization mechanism, 7 is a fast atom beam,
Reference numeral 8 is a power source, 9 and 10 are slits, 11 and 12 are deflection electrodes, and 13 is a collector.

Claims (1)

[Claims] 1. A cathode is disposed on each side of the anode to maintain the anode at a high potential with respect to the cathode, thereby causing glow discharge between the anode and the cathode, and centering the anode between the cathodes. While oscillating the electrons, the cathode is provided with a particle beam outlet and a cylindrical neutralizing mechanism that is directly connected to the particle beam outlet, so that ions passing through the outlet can be treated by the inner wall of the neutralizing mechanism. A high-speed atomic beam source device characterized in that it collides with a high-speed atomic beam.